Systems and methods of audio decoder determination and selection

ABSTRACT

Playback devices can support audio encoded using various encoding schemes. Playing back such content includes receiving, at a playback device, audio data from an audio source; and receiving an indication from the audio source that the audio data is encoded in the compressed audio format. The device determines, independently of receiving the indication from the audio source that the audio data is encoded in the compressed audio format, whether the audio data is encoded in a compressed audio format. If the audio data is determined to be encoded in the compressed audio format: the device selects a decoder from among a plurality of decoders; decodes the audio data using the selected decoder; and plays back the decoded audio data via the playback device. If the audio data is determined not to be encoded in the compressed audio format, the device inhibits playback of the audio data.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.17/249,629, filed Mar. 8, 2021, which claims the benefit of priority toU.S. patent application Ser. No. 62/987,262, filed Mar. 9, 2020, whichare incorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

The present disclosure is related to consumer goods and, moreparticularly, to methods, systems, products, features, services, andother elements directed to media playback or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loudsetting were limited until in 2002, when SONOS, Inc. began developmentof a new type of playback system. Sonos then filed one of its firstpatent applications in 2003, entitled “Method for Synchronizing AudioPlayback between Multiple Networked Devices,” and began offering itsfirst media playback systems for sale in 2005. The Sonos Wireless HomeSound System enables people to experience music from many sources viaone or more networked playback devices. Through a software controlapplication installed on a controller (e.g., smartphone, tablet,computer, voice input device), one can play what she wants in any roomhaving a networked playback device. Media content (e.g., songs,podcasts, video sound) can be streamed to playback devices such thateach room with a playback device can play back corresponding differentmedia content. In addition, rooms can be grouped together forsynchronous playback of the same media content, and/or the same mediacontent can be heard in all rooms synchronously.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, examples, and advantages of the presently disclosed technologymay be better understood with regard to the following description,appended claims, and accompanying drawings, as listed below. A personskilled in the relevant art will understand that the features shown inthe drawings are for purposes of illustrations, and variations,including different and/or additional features and arrangements thereof,are possible.

FIG. 1A is a partial cutaway view of an environment having a mediaplayback system configured in accordance with examples of the disclosedtechnology.

FIG. 1B is a schematic diagram of the media playback system of FIG. 1Aand one or more networks.

FIG. 1C is a block diagram of a playback device.

FIG. 1D is a block diagram of a playback device.

FIG. 1E is a block diagram of a network microphone device.

FIG. 1F is a block diagram of a network microphone device.

FIG. 1G is a block diagram of a playback device.

FIG. 1H is a partially schematic diagram of a control device.

FIG. 2 is a schematic view of a playback device in communication with avideo display device in accordance with examples of the presenttechnology.

FIG. 3 is a flow diagram of a method for decoding audio data inaccordance with examples of the present technology.

FIG. 4 is a flow diagram of another method for decoding audio data inaccordance with examples of the present technology.

FIG. 5 illustrates a state machine for decoding audio data in accordancewith examples of the present technology.

The drawings are for the purpose of illustrating examples of the presenttechnology, but those of ordinary skill in the art will understand thatthe technology disclosed herein is not limited to the arrangementsand/or instrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

Audio input can be encoded using a number of different formats, such asuncompressed pulse-code modulation (PCM), or various types of compressedencoding formats (e.g., Dolby Digital, Dolby Digital Plus, Dolby TrueHD,Dolby Atmos, DTS Digital Surround, DTS-HD High Resolution, DTS-HD MasterAudio, etc.). This is particularly true in the audio component ofaudiovisual media, for example the audio component of television showsor movies. In such cases, a video display device (e.g., a television, astreaming video set-top box, DVD player, etc.) may output audio data toan accompanying playback device such as a soundbar, or a collection ofindividual playback devices grouped to provide surround-sound, etc. Inoperation, the playback device(s) can play back the audio componentsynchronously with video playback via the video display device.

In some cases, the video display device provides to the playback devicean indication of whether the incoming data is encoded using a compressedformat. This indication may take the form of a channel status block(CSB) in the audio data that indicates, in a binary fashion, whether theincoming audio data is encoded in a compressed format. These CSBs areintended to reliably communicate to audio sink or receiver class deviceswhether the incoming audio data is encoded using a compressed format(e.g., DTS Digital Surround, Dolby Digital) or in an uncompressed format(e.g., PCM).

In practice, however, the CSBs are unreliable, and in many instances avideo display device outputs PCM audio data that is erroneouslyindicated to be encoded using a compressed format, or conversely thedevice outputs compressed audio data indicated to be PCM. Thismisidentification can lead to undesirable results in audio playback.Accordingly, relying solely on the CSB to determine handling of incomingaudio data via a playback device can lead to poor user experiences. Inparticular, playing back audio content utilizing a PCM decoding schemewhen the incoming audio data has actually been compressed according toDolby Digital (or another compressed format), for example, would resultin a jarring, undesirable, and often annoying sound. Conversely,playback of audio content may fail altogether if the playback deviceutilizes a compressed decoding scheme when the incoming data is actuallyuncompressed PCM.

In addition to differentiating between compressed and uncompressed audioformats, it may be important to differentiate between different types ofcompressed audio formats. For example, a playback device may support anumber of different compressed audio formats. Each format may require adifferent processing scheme to correctly decode and play back thecompressed audio data. In some examples of the present technology, theincoming audio data can be analyzed to identify the particularcompressed audio format and, based on this identification, select anappropriate audio decoding scheme.

Accordingly, in order to provide for improved user experiences, and toreliably route incoming audio data to an appropriate decoder, thereremains a need for more intelligent analysis of audio data provided froma video display device. As described in more detail herein, in someexamples the playback device can examine the incoming audio data anddetermine, independently of any indication (e.g., CSB) provided by thevideo display device, whether the audio data is encoded using acompressed format. The analysis can further determine which encodingformat is used, and whether the playback device supports playback of theidentified format.

While some examples described herein may refer to functions performed bygiven actors such as “users,” “listeners,” and/or other entities, itshould be understood that this is for purposes of explanation only. Theclaims should not be interpreted to require action by any such exampleactor unless explicitly required by the language of the claimsthemselves.

In the Figures, identical reference numbers identify generally similar,and/or identical, elements. To facilitate the discussion of anyparticular element, the most significant digit or digits of a referencenumber refers to the Figure in which that element is first introduced.For example, element 110 a is first introduced and discussed withreference to FIG. 1A. Many of the details, dimensions, angles and otherfeatures shown in the Figures are merely illustrative of particularexamples of the disclosed technology. Accordingly, other examples canhave other details, dimensions, angles and features without departingfrom the spirit or scope of the disclosure. In addition, those ofordinary skill in the art will appreciate that further examples of thevarious disclosed technologies can be practiced without several of thedetails described below.

II. Suitable Operating Environment

FIG. 1A is a partial cutaway view of a media playback system 100distributed in an environment 101 (e.g., a house). The media playbacksystem 100 comprises one or more playback devices 110 (identifiedindividually as playback devices 110 a-n), one or more networkmicrophone devices (“NMDs”), 120 (identified individually as NMDs 120a-c), and one or more control devices 130 (identified individually ascontrol devices 130 a and 130 b).

As used herein the term “playback device” can generally refer to anetwork device configured to receive, process, and output data of amedia playback system. For example, a playback device can be a networkdevice that receives and processes audio content. In some examples, aplayback device includes one or more transducers or speakers powered byone or more amplifiers. In other examples, however, a playback deviceincludes one of (or neither of) the speaker and the amplifier. Forinstance, a playback device can comprise one or more amplifiersconfigured to drive one or more speakers external to the playback devicevia a corresponding wire or cable.

Moreover, as used herein the term NMD (i.e., a “network microphonedevice”) can generally refer to a network device that is configured foraudio detection. In some examples, an NMD is a stand-alone deviceconfigured primarily for audio detection. In other examples, an NMD isincorporated into a playback device (or vice versa).

The term “control device” can generally refer to a network deviceconfigured to perform functions relevant to facilitating user access,control, and/or configuration of the media playback system 100.

Each of the playback devices 110 is configured to receive audio signalsor data from one or more media sources (e.g., one or more remoteservers, one or more local devices) and play back the received audiosignals or data as sound. The one or more NMDs 120 are configured toreceive spoken word commands, and the one or more control devices 130are configured to receive user input. In response to the received spokenword commands and/or user input, the media playback system 100 can playback audio via one or more of the playback devices 110. In certainexamples, the playback devices 110 are configured to commence playbackof media content in response to a trigger. For instance, one or more ofthe playback devices 110 can be configured to play back a morningplaylist upon detection of an associated trigger condition (e.g.,presence of a user in a kitchen, detection of a coffee machineoperation). In some examples, for instance, the media playback system100 is configured to play back audio from a first playback device (e.g.,the playback device 110 a) in synchrony with a second playback device(e.g., the playback device 110 b). Interactions between the playbackdevices 110, NMDs 120, and/or control devices 130 of the media playbacksystem 100 configured in accordance with the various examples of thedisclosure are described in greater detail below.

In the illustrated example of FIG. 1A, the environment 101 comprises ahousehold having several rooms, spaces, and/or playback zones, including(clockwise from upper left) a master bathroom 101 a, a master bedroom101 b, a second bedroom 101 c, a family room or den 101 d, an office 101e, a living room 101 f, a dining room 101 g, a kitchen 101 h, and anoutdoor patio 101 i. While certain examples are described below in thecontext of a home environment, the technologies described herein may beimplemented in other types of environments. In some examples, forinstance, the media playback system 100 can be implemented in one ormore commercial settings (e.g., a restaurant, mall, airport, hotel, aretail or other store), one or more vehicles (e.g., a sports utilityvehicle, bus, car, a ship, a boat, an airplane), multiple environments(e.g., a combination of home and vehicle environments), and/or anothersuitable environment where multi-zone audio may be desirable.

The media playback system 100 can comprise one or more playback zones,some of which may correspond to the rooms in the environment 101. Themedia playback system 100 can be established with one or more playbackzones, after which additional zones may be added, or removed to form,for example, the configuration shown in FIG. 1A. Each zone may be givena name according to a different room or space such as the office 101 e,master bathroom 101 a, master bedroom 101 b, the second bedroom 101 c,kitchen 101 h, dining room 101 g, living room 101 f, and/or the balcony101 i. In some examples, a single playback zone may include multiplerooms or spaces. In certain examples, a single room or space may includemultiple playback zones.

In the illustrated example of FIG. 1A, the master bathroom 101 a, thesecond bedroom 101 c, the office 101 e, the living room 101 f, thedining room 101 g, the kitchen 101 h, and the outdoor patio 101 i eachinclude one playback device 110, and the master bedroom 101 b and theden 101 d include a plurality of playback devices 110. In the masterbedroom 101 b, the playback devices 110 l and 110 m may be configured,for example, to play back audio content in synchrony as individual onesof playback devices 110, as a bonded playback zone, as a consolidatedplayback device, and/or any combination thereof. Similarly, in the den101 d, the playback devices 110 h-j can be configured, for instance, toplay back audio content in synchrony as individual ones of playbackdevices 110, as one or more bonded playback devices, and/or as one ormore consolidated playback devices. Additional details regarding bondedand consolidated playback devices are described below with respect toFIGS. 1B and 1E.

In some examples, one or more of the playback zones in the environment101 may each be playing different audio content. For instance, a usermay be grilling on the patio 101 i and listening to hip hop music beingplayed by the playback device 110 c while another user is preparing foodin the kitchen 101 h and listening to classical music played by theplayback device 110 b. In another example, a playback zone may play thesame audio content in synchrony with another playback zone. Forinstance, the user may be in the office 101 e listening to the playbackdevice 110 f playing back the same hip-hop music being played back byplayback device 110 c on the patio 101 i. In some examples, the playbackdevices 110 c and 110 f play back the hip hop music in synchrony suchthat the user perceives that the audio content is being playedseamlessly (or at least substantially seamlessly) while moving betweendifferent playback zones. Additional details regarding audio playbacksynchronization among playback devices and/or zones can be found, forexample, in U.S. Pat. No. 8,234,395 entitled, “System and method forsynchronizing operations among a plurality of independently clockeddigital data processing devices,” which is incorporated herein byreference in its entirety.

a. Suitable Media Playback System

FIG. 1B is a schematic diagram of the media playback system 100 and acloud network 102. For ease of illustration, certain devices of themedia playback system 100 and the cloud network 102 are omitted fromFIG. 1B. One or more communication links 103 (referred to hereinafter as“the links 103”) communicatively couple the media playback system 100and the cloud network 102.

The links 103 can comprise, for example, one or more wired networks, oneor more wireless networks, one or more wide area networks (WAN), one ormore local area networks (LAN), one or more personal area networks(PAN), one or more telecommunication networks (e.g., one or more GlobalSystem for Mobiles (GSM) networks, Code Division Multiple Access (CDMA)networks, Long-Term Evolution (LTE) networks, 5G communication networknetworks, and/or other suitable data transmission protocol networks),etc. The cloud network 102 is configured to deliver media content (e.g.,audio content, video content, photographs, social media content) to themedia playback system 100 in response to a request transmitted from themedia playback system 100 via the links 103. In some examples, the cloudnetwork 102 is further configured to receive data (e.g. voice inputdata) from the media playback system 100 and correspondingly transmitcommands and/or media content to the media playback system 100.

The cloud network 102 comprises computing devices 106 (identifiedseparately as a first computing device 106 a, a second computing device106 b, and a third computing device 106 c). The computing devices 106can comprise individual computers or servers, such as, for example, amedia streaming service server storing audio and/or other media content,a voice service server, a social media server, a media playback systemcontrol server, etc. In some examples, one or more of the computingdevices 106 comprise modules of a single computer or server. In certainexamples, one or more of the computing devices 106 comprise one or moremodules, computers, and/or servers. Moreover, while the cloud network102 is described above in the context of a single cloud network, in someexamples the cloud network 102 comprises a plurality of cloud networkscomprising communicatively coupled computing devices. Furthermore, whilethe cloud network 102 is shown in FIG. 1B as having three of thecomputing devices 106, in some examples, the cloud network 102 comprisesfewer (or more than) three computing devices 106.

The media playback system 100 is configured to receive media contentfrom the networks 102 via the links 103. The received media content cancomprise, for example, a Uniform Resource Identifier (URI) and/or aUniform Resource Locator (URL). For instance, in some examples, themedia playback system 100 can stream, download, or otherwise obtain datafrom a URI or a URL corresponding to the received media content. Anetwork 104 communicatively couples the links 103 and at least a portionof the devices (e.g., one or more of the playback devices 110, NMDs 120,and/or control devices 130) of the media playback system 100. Thenetwork 104 can include, for example, a wireless network (e.g., a Wi-Finetwork, a Bluetooth, a Z-Wave network, a ZigBee, and/or other suitablewireless communication protocol network) and/or a wired network (e.g., anetwork comprising Ethernet, Universal Serial Bus (USB), and/or anothersuitable wired communication). As those of ordinary skill in the artwill appreciate, as used herein, “Wi-Fi” can refer to several differentcommunication protocols including, for example, Institute of Electricaland Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.11ac, 802.11ad, 802.11af, 802.11ah, 802.11ai, 802.11aj,802.11aq, 802.11ax, 802.1lay, 802.15, etc. transmitted at 2.4 Gigahertz(GHz), 5 GHz, and/or another suitable frequency.

In some examples, the network 104 comprises a dedicated communicationnetwork that the media playback system 100 uses to transmit messagesbetween individual devices and/or to transmit media content to and frommedia content sources (e.g., one or more of the computing devices 106).In certain examples, the network 104 is configured to be accessible onlyto devices in the media playback system 100, thereby reducinginterference and competition with other household devices. In otherexamples, however, the network 104 comprises an existing householdcommunication network (e.g., a household Wi-Fi network). In someexamples, the links 103 and the network 104 comprise one or more of thesame networks. In some examples, for instance, the links 103 and thenetwork 104 comprise a telecommunication network (e.g., an LTE network,a 5G network). Moreover, in some examples, the media playback system 100is implemented without the network 104, and devices comprising the mediaplayback system 100 can communicate with each other, for example, viaone or more direct connections, PANs, telecommunication networks, and/orother suitable communication links.

In some examples, audio content sources may be regularly added orremoved from the media playback system 100. In some examples, forinstance, the media playback system 100 performs an indexing of mediaitems when one or more media content sources are updated, added to,and/or removed from the media playback system 100. The media playbacksystem 100 can scan identifiable media items in some or all foldersand/or directories accessible to the playback devices 110, and generateor update a media content database comprising metadata (e.g., title,artist, album, track length) and other associated information (e.g.,URIs, URLs) for each identifiable media item found. In some examples,for instance, the media content database is stored on one or more of theplayback devices 110, network microphone devices 120, and/or controldevices 130.

In the illustrated example of FIG. 1B, the playback devices 110 l and110 m comprise a group 107 a. The playback devices 110 l and 110 m canbe positioned in different rooms in a household and be grouped togetherin the group 107 a on a temporary or permanent basis based on user inputreceived at the control device 130 a and/or another control device 130in the media playback system 100. When arranged in the group 107 a, theplayback devices 110 l and 110 m can be configured to play back the sameor similar audio content in synchrony from one or more audio contentsources. In certain examples, for instance, the group 107 a comprises abonded zone in which the playback devices 110 l and 110 m comprise leftaudio and right audio channels, respectively, of multi-channel audiocontent, thereby producing or enhancing a stereo effect of the audiocontent. In some examples, the group 107 a includes additional playbackdevices 110. In other examples, however, the media playback system 100omits the group 107 a and/or other grouped arrangements of the playbackdevices 110.

The media playback system 100 includes the NMDs 120 a and 120 d, eachcomprising one or more microphones configured to receive voiceutterances from a user. In the illustrated example of FIG. 1B, the NMD120 a is a standalone device and the NMD 120 d is integrated into theplayback device 110 n. The NMD 120 a, for example, is configured toreceive voice input 121 from a user 123. In some examples, the NMD 120 atransmits data associated with the received voice input 121 to a voiceassistant service (VAS) configured to (i) process the received voiceinput data and (ii) transmit a corresponding command to the mediaplayback system 100. In some examples, for instance, the computingdevice 106 c comprises one or more modules and/or servers of a VAS(e.g., a VAS operated by one or more of SONOS®, AMAZON®, GOOGLE® APPLE®,MICROSOFT®). The computing device 106 c can receive the voice input datafrom the NMD 120 a via the network 104 and the links 103. In response toreceiving the voice input data, the computing device 106 c processes thevoice input data (i.e., “Play Hey Jude by The Beatles”), and determinesthat the processed voice input includes a command to play a song (e.g.,“Hey Jude”). The computing device 106 c accordingly transmits commandsto the media playback system 100 to play back “Hey Jude” by the Beatlesfrom a suitable media service (e.g., via one or more of the computingdevices 106) on one or more of the playback devices 110.

b. Suitable Playback Devices

FIG. 1C is a block diagram of the playback device 110 a comprising aninput/output 111. The input/output 111 can include an analog I/O 111 a(e.g., one or more wires, cables, and/or other suitable communicationlinks configured to carry analog signals) and/or a digital I/O 111 b(e.g., one or more wires, cables, or other suitable communication linksconfigured to carry digital signals). In some examples, the analog I/O111 a is an audio line-in input connection comprising, for example, anauto-detecting 3.5 mm audio line-in connection. In some examples, thedigital I/O 111 b comprises a Sony/Philips Digital Interface Format(S/PDIF) communication interface and/or cable and/or a Toshiba Link(TOSLINK) cable. In some examples, the digital I/O 111 b comprises aHigh-Definition Multimedia Interface (HDMI) interface and/or cable. Insome examples, the digital I/O 111 b includes one or more wirelesscommunication links comprising, for example, a radio frequency (RF),infrared, WiFi, Bluetooth, or another suitable communication protocol.In certain examples, the analog I/O 111 a and the digital 111 b compriseinterfaces (e.g., ports, plugs, jacks) configured to receive connectorsof cables transmitting analog and digital signals, respectively, withoutnecessarily including cables.

The playback device 110 a, for example, can receive media content (e.g.,audio content comprising music and/or other sounds) from a local audiosource 105 via the input/output 111 (e.g., a cable, a wire, a PAN, aBluetooth connection, an ad hoc wired or wireless communication network,and/or another suitable communication link). The local audio source 105can comprise, for example, a mobile device (e.g., a smartphone, atablet, a laptop computer) or another suitable audio component (e.g., atelevision, a desktop computer, an amplifier, a phonograph, a Blu-rayplayer, a memory storing digital media files). In some examples, thelocal audio source 105 includes a video display device (e.g., atelevision, display, Blu-ray player, streaming set-top box, etc.)configured to play back video (or output video to another device) insynchrony with audio playback via the playback device 110 a. In someexamples, the local audio source 105 includes local music libraries on asmartphone, a computer, a networked-attached storage (NAS), and/oranother suitable device configured to store media files. In certainexamples, one or more of the playback devices 110, NMDs 120, and/orcontrol devices 130 comprise the local audio source 105. In otherexamples, however, the media playback system omits the local audiosource 105 altogether. In some examples, the playback device 110 a doesnot include an input/output 111 and receives all audio content via thenetwork 104.

The playback device 110 a further comprises electronics 112, a userinterface 113 (e.g., one or more buttons, knobs, dials, touch-sensitivesurfaces, displays, touchscreens), and one or more transducers 114(referred to hereinafter as “the transducers 114”). The electronics 112is configured to receive audio from an audio source (e.g., the localaudio source 105) via the input/output 111, one or more of the computingdevices 106 a-c via the network 104 (FIG. 1B)), amplify the receivedaudio, and output the amplified audio for playback via one or more ofthe transducers 114. In some examples, the playback device 110 aoptionally includes one or more microphones 115 (e.g., a singlemicrophone, a plurality of microphones, a microphone array) (hereinafterreferred to as “the microphones 115”). In certain examples, forinstance, the playback device 110 a having one or more of the optionalmicrophones 115 can operate as an NMD configured to receive voice inputfrom a user and correspondingly perform one or more operations based onthe received voice input.

In the illustrated example of FIG. 1C, the electronics 112 comprise oneor more processors 112 a (referred to hereinafter as “the processors 112a”), memory 112 b, software components 112 c, a network interface 112 d,one or more audio processing components 112 g (referred to hereinafteras “the audio components 112 g”), one or more audio amplifiers 112 h(referred to hereinafter as “the amplifiers 112 h”), and power 112 i(e.g., one or more power supplies, power cables, power receptacles,batteries, induction coils, Power-over Ethernet (POE) interfaces, and/orother suitable sources of electric power). In some examples, theelectronics 112 optionally include one or more other components 112 j(e.g., one or more sensors, video displays, touchscreens, batterycharging bases).

The processors 112 a can comprise clock-driven computing component(s)configured to process data, and the memory 112 b can comprise acomputer-readable medium (e.g., a tangible, non-transitorycomputer-readable medium, data storage loaded with one or more of thesoftware components 112 c) configured to store instructions forperforming various operations and/or functions. The processors 112 a areconfigured to execute the instructions stored on the memory 112 b toperform one or more of the operations. The operations can include, forexample, causing the playback device 110 a to retrieve audio data froman audio source (e.g., one or more of the computing devices 106 a-c(FIG. 1B)), and/or another one of the playback devices 110. In someexamples, the operations further include causing the playback device 110a to send audio data to another one of the playback devices 110 a and/oranother device (e.g., one of the NMDs 120). Certain examples includeoperations causing the playback device 110 a to pair with another of theone or more playback devices 110 to enable a multi-channel audioenvironment (e.g., a stereo pair, a bonded zone).

The processors 112 a can be further configured to perform operationscausing the playback device 110 a to synchronize playback of audiocontent with another of the one or more playback devices 110. As thoseof ordinary skill in the art will appreciate, during synchronousplayback of audio content on a plurality of playback devices, a listenerwill preferably be unable to perceive time-delay differences betweenplayback of the audio content by the playback device 110 a and the otherone or more other playback devices 110. Additional details regardingaudio playback synchronization among playback devices can be found, forexample, in U.S. Pat. No. 8,234,395, which was incorporated by referenceabove.

In some examples, the memory 112 b is further configured to store dataassociated with the playback device 110 a, such as one or more zonesand/or zone groups of which the playback device 110 a is a member, audiosources accessible to the playback device 110 a, and/or a playback queuethat the playback device 110 a (and/or another of the one or moreplayback devices) can be associated with. The stored data can compriseone or more state variables that are periodically updated and used todescribe a state of the playback device 110 a. The memory 112 b can alsoinclude data associated with a state of one or more of the other devices(e.g., the playback devices 110, NMDs 120, control devices 130) of themedia playback system 100. In some examples, for instance, the statedata is shared during predetermined intervals of time (e.g., every 5seconds, every 10 seconds, every 60 seconds) among at least a portion ofthe devices of the media playback system 100, so that one or more of thedevices have the most recent data associated with the media playbacksystem 100.

The network interface 112 d is configured to facilitate a transmissionof data between the playback device 110 a and one or more other deviceson a data network such as, for example, the links 103 and/or the network104 (FIG. 1B). The network interface 112 d is configured to transmit andreceive data corresponding to media content (e.g., audio content, videocontent, text, photographs) and other signals (e.g., non-transitorysignals) comprising digital packet data including an Internet Protocol(IP)-based source address and/or an IP-based destination address.

The network interface 112 d can parse the digital packet data such thatthe electronics 112 properly receives and processes the data destinedfor the playback device 110 a.

In the illustrated example of FIG. 1C, the network interface 112 dcomprises one or more wireless interfaces 112 e (referred to hereinafteras “the wireless interface 112 e”). The wireless interface 112 e (e.g.,a suitable interface comprising one or more antennae) can be configuredto wirelessly communicate with one or more other devices (e.g., one ormore of the other playback devices 110, NMDs 120, and/or control devices130) that are communicatively coupled to the network 104 (FIG. 1B) inaccordance with a suitable wireless communication protocol (e.g., Wi-Fi,Bluetooth, LTE). In some examples, the network interface 112 doptionally includes a wired interface 112 f (e.g., an interface orreceptacle configured to receive a network cable such as an Ethernet, aUSB-A, USB-C, and/or Thunderbolt cable) configured to communicate over awired connection with other devices in accordance with a suitable wiredcommunication protocol. In certain examples, the network interface 112 dincludes the wired interface 112 f and excludes the wireless interface112 e. In some examples, the electronics 112 excludes the networkinterface 112 d altogether and transmits and receives media contentand/or other data via another communication path (e.g., the input/output111).

The audio components 112 g are configured to process and/or filter datacomprising media content received by the electronics 112 (e.g., via theinput/output 111 and/or the network interface 112 d) to produce outputaudio signals. In some examples, the audio processing components 112 gcomprise, for example, one or more digital-to-analog converters (DAC),audio preprocessing components, audio enhancement components, a digitalsignal processors (DSPs), and/or other suitable audio processingcomponents, modules, circuits, etc. In some examples, the audioprocessing components 112 g can comprise, for example, one or more audiodecoders configured to facilitate playback of audio encoded in aparticular format (e.g., pulse-code modulation (PCM), Dolby Digital,DTS, etc.). In certain examples, one or more of the audio processingcomponents 112 g can comprise one or more subcomponents of theprocessors 112 a. In some examples, the electronics 112 omits the audioprocessing components 112 g. In some examples, for instance, theprocessors 112 a execute instructions stored on the memory 112 b toperform audio processing operations to produce the output audio signals.

The amplifiers 112 h are configured to receive and amplify the audiooutput signals produced by the audio processing components 112 g and/orthe processors 112 a. The amplifiers 112 h can comprise electronicdevices and/or components configured to amplify audio signals to levelssufficient for driving one or more of the transducers 114. In someexamples, for instance, the amplifiers 112 h include one or moreswitching or class-D power amplifiers. In other examples, however, theamplifiers include one or more other types of power amplifiers (e.g.,linear gain power amplifiers, class-A amplifiers, class-B amplifiers,class-AB amplifiers, class-C amplifiers, class-D amplifiers, class-Eamplifiers, class-F amplifiers, class-G and/or class H amplifiers,and/or another suitable type of power amplifier). In certain examples,the amplifiers 112 h comprise a suitable combination of two or more ofthe foregoing types of power amplifiers. Moreover, in some examples,individual ones of the amplifiers 112 h correspond to individual ones ofthe transducers 114. In other examples, however, the electronics 112includes a single one of the amplifiers 112 h configured to outputamplified audio signals to a plurality of the transducers 114. In someother examples, the electronics 112 omits the amplifiers 112 h.

The transducers 114 (e.g., one or more speakers and/or speaker drivers)receive the amplified audio signals from the amplifier 112 h and renderor output the amplified audio signals as sound (e.g., audible soundwaves having a frequency between about 20 Hertz (Hz) and 20 kilohertz(kHz)). In some examples, the transducers 114 can comprise a singletransducer. In other examples, however, the transducers 114 comprise aplurality of audio transducers. In some examples, the transducers 114comprise more than one type of transducer. For example, the transducers114 can include one or more low frequency transducers (e.g., subwoofers,woofers), mid-range frequency transducers (e.g., mid-range transducers,mid-woofers), and one or more high frequency transducers (e.g., one ormore tweeters). As used herein, “low frequency” can generally refer toaudible frequencies below about 500 Hz, “mid-range frequency” cangenerally refer to audible frequencies between about 500 Hz and about 2kHz, and “high frequency” can generally refer to audible frequenciesabove 2 kHz. In certain examples, however, one or more of thetransducers 114 comprise transducers that do not adhere to the foregoingfrequency ranges. For example, one of the transducers 114 may comprise amid-woofer transducer configured to output sound at frequencies betweenabout 200 Hz and about 5 kHz.

By way of illustration, SONOS, Inc. presently offers (or has offered)for sale certain playback devices including, for example, a “SONOS ONE,”“MOVE,” “PLAY:5,” “BEAM,” “PLAYBAR,” “PLAYBASE,” “PORT,” “BOOST,” “AMP,”and “SUB.” Other suitable playback devices may additionally oralternatively be used to implement the playback devices of examplesdisclosed herein. Additionally, one of ordinary skilled in the art willappreciate that a playback device is not limited to the examplesdescribed herein or to SONOS product offerings. In some examples, forinstance, one or more playback devices 110 comprises wired or wirelessheadphones (e.g., over-the-ear headphones, on-ear headphones, in-earearphones). In other examples, one or more of the playback devices 110comprise a docking station and/or an interface configured to interactwith a docking station for personal mobile media playback devices. Incertain examples, a playback device may be integral to another device orcomponent such as a television, a lighting fixture, or some other devicefor indoor or outdoor use. In some examples, a playback device omits auser interface and/or one or more transducers. For example, FIG. 1D is ablock diagram of a playback device 110 p comprising the input/output 111and electronics 112 without the user interface 113 or transducers 114.

FIG. 1E is a block diagram of a bonded playback device 110 q comprisingthe playback device 110 a (FIG. 1C) sonically bonded with the playbackdevice 110 i (e.g., a subwoofer) (FIG. 1A). In the illustrated example,the playback devices 110 a and 110 i are separate ones of the playbackdevices 110 housed in separate enclosures. In some examples, however,the bonded playback device 110 q comprises a single enclosure housingboth the playback devices 110 a and 110 i. The bonded playback device110 q can be configured to process and reproduce sound differently thanan unbonded playback device (e.g., the playback device 110 a of FIG. 1C)and/or paired or bonded playback devices (e.g., the playback devices 110l and 110 m of FIG. 1B). In some examples, for instance, the playbackdevice 110 a is full-range playback device configured to render lowfrequency, mid-range frequency, and high frequency audio content, andthe playback device 110 i is a subwoofer configured to render lowfrequency audio content. In some examples, the playback device 110 a,when bonded with the first playback device, is configured to render onlythe mid-range and high frequency components of a particular audiocontent, while the playback device 110 i renders the low frequencycomponent of the particular audio content. In some examples, the bondedplayback device 110 q includes additional playback devices and/oranother bonded playback device. Additional playback device examples aredescribed in further detail below with respect to FIGS. 2A-2C.

c. Suitable Network Microphone Devices (NMDs)

FIG. 1F is a block diagram of the NMD 120 a (FIGS. 1A and 1B). The NMD120 a includes one or more voice processing components 124 (hereinafter“the voice components 124”) and several components described withrespect to the playback device 110 a (FIG. 1C) including the processors112 a, the memory 112 b, and the microphones 115. The NMD 120 aoptionally comprises other components also included in the playbackdevice 110 a (FIG. 1C), such as the user interface 113 and/or thetransducers 114. In some examples, the NMD 120 a is configured as amedia playback device (e.g., one or more of the playback devices 110),and further includes, for example, one or more of the audio components112 g (FIG. 1C), the amplifiers 114, and/or other playback devicecomponents. In certain examples, the NMD 120 a comprises an Internet ofThings (IoT) device such as, for example, a thermostat, alarm panel,fire and/or smoke detector, etc. In some examples, the NMD 120 acomprises the microphones 115, the voice processing components 124, andonly a portion of the components of the electronics 112 described abovewith respect to FIG. 1B. In some examples, for instance, the NMD 120 aincludes the processor 112 a and the memory 112 b (FIG. 1B), whileomitting one or more other components of the electronics 112. In someexamples, the NMD 120 a includes additional components (e.g., one ormore sensors, cameras, thermometers, barometers, hygrometers).

In some examples, an NMD can be integrated into a playback device. FIG.1G is a block diagram of a playback device 110 r comprising an NMD 120d. The playback device 110 r can comprise many or all of the componentsof the playback device 110 a and further include the microphones 115 andvoice processing components 124 (FIG. 1F). The playback device 110 roptionally includes an integrated control device 130 c. The controldevice 130 c can comprise, for example, a user interface (e.g., the userinterface 113 of FIG. 1B) configured to receive user input (e.g., touchinput, voice input) without a separate control device. In otherexamples, however, the playback device 110 r receives commands fromanother control device (e.g., the control device 130 a of FIG. 1B).

Referring again to FIG. 1F, the microphones 115 are configured toacquire, capture, and/or receive sound from an environment (e.g., theenvironment 101 of FIG. 1A) and/or a room in which the NMD 120 a ispositioned. The received sound can include, for example, vocalutterances, audio played back by the NMD 120 a and/or another playbackdevice, background voices, ambient sounds, etc. The microphones 115convert the received sound into electrical signals to produce microphonedata. The voice processing components 124 receive and analyzes themicrophone data to determine whether a voice input is present in themicrophone data. The voice input can comprise, for example, anactivation word followed by an utterance including a user request. Asthose of ordinary skill in the art will appreciate, an activation wordis a word or other audio cue that signifying a user voice input. Forinstance, in querying the AMAZON® VAS, a user might speak the activationword “Alexa.” Other examples include “Ok, Google” for invoking theGOOGLE® VAS and “Hey, Siri” for invoking the APPLE® VAS.

After detecting the activation word, voice processing components 124monitor the microphone data for an accompanying user request in thevoice input. The user request may include, for example, a command tocontrol a third-party device, such as a thermostat (e.g., NEST®thermostat), an illumination device (e.g., a PHILIPS HUE® lightingdevice), or a media playback device (e.g., a Sonos® playback device).For example, a user might speak the activation word “Alexa” followed bythe utterance “set the thermostat to 68 degrees” to set a temperature ina home (e.g., the environment 101 of FIG. 1A). The user might speak thesame activation word followed by the utterance “turn on the living room”to turn on illumination devices in a living room area of the home. Theuser may similarly speak an activation word followed by a request toplay a particular song, an album, or a playlist of music on a playbackdevice in the home.

d. Suitable Control Devices

FIG. 1H is a partially schematic diagram of the control device 130 a(FIGS. 1A and 1B). As used herein, the term “control device” can be usedinterchangeably with “controller” or “control system.” Among otherfeatures, the control device 130 a is configured to receive user inputrelated to the media playback system 100 and, in response, cause one ormore devices in the media playback system 100 to perform an action(s) oroperation(s) corresponding to the user input. In the illustratedexample, the control device 130 a comprises a smartphone (e.g., aniPhone™, an Android phone) on which media playback system controllerapplication software is installed. In some examples, the control device130 a comprises, for example, a tablet (e.g., an iPad™), a computer(e.g., a laptop computer, a desktop computer), and/or another suitabledevice (e.g., a television, an automobile audio head unit, an IoTdevice). In certain examples, the control device 130 a comprises adedicated controller for the media playback system 100. In otherexamples, as described above with respect to FIG. 1G, the control device130 a is integrated into another device in the media playback system 100(e.g., one more of the playback devices 110, NMDs 120, and/or othersuitable devices configured to communicate over a network).

The control device 130 a includes electronics 132, a user interface 133,one or more speakers 134, and one or more microphones 135. Theelectronics 132 comprise one or more processors 132 a (referred tohereinafter as “the processors 132 a”), a memory 132 b, softwarecomponents 132 c, and a network interface 132 d. The processor 132 a canbe configured to perform functions relevant to facilitating user access,control, and configuration of the media playback system 100. The memory132 b can comprise data storage that can be loaded with one or more ofthe software components executable by the processor 132 a to performthose functions. The software components 132 c can comprise applicationsand/or other executable software configured to facilitate control of themedia playback system 100. The memory 112 b can be configured to store,for example, the software components 132 c, media playback systemcontroller application software, and/or other data associated with themedia playback system 100 and the user.

The network interface 132 d is configured to facilitate networkcommunications between the control device 130 a and one or more otherdevices in the media playback system 100, and/or one or more remotedevices. In some examples, the network interface 132 d is configured tooperate according to one or more suitable communication industrystandards (e.g., infrared, radio, wired standards including IEEE 802.3,wireless standards including IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.15, 4G, LTE). The network interface 132 d can beconfigured, for example, to transmit data to and/or receive data fromthe playback devices 110, the NMDs 120, other ones of the controldevices 130, one of the computing devices 106 of FIG. 1B, devicescomprising one or more other media playback systems, etc. Thetransmitted and/or received data can include, for example, playbackdevice control commands, state variables, playback zone and/or zonegroup configurations. For instance, based on user input received at theuser interface 133, the network interface 132 d can transmit a playbackdevice control command (e.g., volume control, audio playback control,audio content selection) from the control device 130 to one or more ofthe playback devices 110. The network interface 132 d can also transmitand/or receive configuration changes such as, for example,adding/removing one or more playback devices 110 to/from a zone,adding/removing one or more zones to/from a zone group, forming a bondedor consolidated player, separating one or more playback devices from abonded or consolidated player, among others.

The user interface 133 is configured to receive user input and canfacilitate ‘control of the media playback system 100. The user interface133 includes media content art 133 a (e.g., album art, lyrics, videos),a playback status indicator 133 b (e.g., an elapsed and/or remainingtime indicator), media content information region 133 c, a playbackcontrol region 133 d, and a zone indicator 133 e. The media contentinformation region 133 c can include a display of relevant information(e.g., title, artist, album, genre, release year) about media contentcurrently playing and/or media content in a queue or playlist. Theplayback control region 133 d can include selectable (e.g., via touchinput and/or via a cursor or another suitable selector) icons to causeone or more playback devices in a selected playback zone or zone groupto perform playback actions such as, for example, play or pause, fastforward, rewind, skip to next, skip to previous, enter/exit shufflemode, enter/exit repeat mode, enter/exit cross fade mode, etc. Theplayback control region 133 d may also include selectable icons tomodify equalization settings, playback volume, and/or other suitableplayback actions. In the illustrated example, the user interface 133comprises a display presented on a touch screen interface of asmartphone (e.g., an iPhone™, an Android phone). In some examples,however, user interfaces of varying formats, styles, and interactivesequences may alternatively be implemented on one or more networkdevices to provide comparable control access to a media playback system.

The one or more speakers 134 (e.g., one or more transducers) can beconfigured to output sound to the user of the control device 130 a. Insome examples, the one or more speakers comprise individual transducersconfigured to correspondingly output low frequencies, mid-rangefrequencies, and/or high frequencies. In some examples, for instance,the control device 130 a is configured as a playback device (e.g., oneof the playback devices 110). Similarly, in some examples the controldevice 130 a is configured as an NMD (e.g., one of the NMDs 120),receiving voice commands and other sounds via the one or moremicrophones 135.

The one or more microphones 135 can comprise, for example, one or morecondenser microphones, electret condenser microphones, dynamicmicrophones, and/or other suitable types of microphones or transducers.In some examples, two or more of the microphones 135 are arranged tocapture location information of an audio source (e.g., voice, audiblesound) and/or configured to facilitate filtering of background noise.Moreover, in certain examples, the control device 130 a is configured tooperate as playback device and an NMD. In other examples, however, thecontrol device 130 a omits the one or more speakers 134 and/or the oneor more microphones 135. For instance, the control device 130 a maycomprise a device (e.g., a thermostat, an IoT device, a network device)comprising a portion of the electronics 132 and the user interface 133(e.g., a touch screen) without any speakers or microphones.

III. Example Systems and Method for Audio Decoder Selection

FIG. 2 is a schematic view of a playback device 210 in communicationwith a video display device 205 in accordance with examples of thepresent technology. In some examples, the playback device 210 (e.g., asoundbar or other suitable playback device) can be configured to playback audio accompanying video that is played back via the separate videodisplay device 205. In the illustrated example, the video display device205 is a television, and there is a physical connection (e.g., wire,cable, etc.) that carries audio input from the display device 205 to theplayback device 210. However, in other examples, a wireless signal(e.g., Wifi, Bluetooth) connects the display device 205 to the playbackdevice 210 without a wire or other physical connection. In someexamples, instead of or in addition to a television, the video displaydevice can be, for example, a streaming device (e.g., APPLE TV, GOOGLECHROMECAST, etc.), a Blu-ray player, or any other such device thatsimultaneously sends video content to a display device such as aprojector or television and also sends audio content to accompanyingaudio devices (e.g., playback device 210). Although a soundbar is shownin this example, the playback device 210 can take any suitable form,including multiple different playback devices that have been groupedtogether for synchronous playback, such as in a home theatresurround-sound configuration.

In operation, the video display device 205 can provide audio data to theplayback device 210 for audio playback. The audio data may be providedin any suitable format, including, for instance, both uncompressed audio(e.g. audio encoded using pulse-code modulation (PCM)) and compressedaudio (e.g., audio encoded using Dolby Digital, Dolby Digital Plus,Dolby TrueHD, Dolby Atmos, DTS Digital Surround, DTS-HD High Resolution,DTS-HD Master Audio, or other encoding scheme that involves compressionof the audio data). To effectively play back the audio content, theplayback device 210 decodes the audio data utilizing the appropriatedecoding scheme. For example, PCM audio data may be handled using oneprocessing scheme, while DTS-encoded audio data may be decoded using adifferent processing scheme. Applying an incorrect processing scheme tothe incoming encoded audio data can result in failure either in the formof no audio output or audio output that scrambles the intended output(e.g., movie dialogue being output in a scrambled manner may sound likegunfire). While video display devices often designate the particularformat of incoming audio content (particularly compressed vs.uncompressed audio), such indications are not always reliable and mayvary from one manufacturer to the next. To ensure the playback device210 appropriately decodes incoming audio data from the video displaydevice 205, the playback device 210 can process incoming audio using oneor more of the methods described herein.

FIG. 3 is a flow diagram of a process 300 for decoding audio data inaccordance with examples of the present technology. In some examples,the process 300 includes one or more instructions stored in memory(e.g., the memory 112 b of FIG. 1) and executed by one or moreprocessors (e.g., the processor 112 a of FIG. 1) of a playback device(e.g., the playback device 110 of FIG. 1, the playback device 205 ofFIG. 2). Although the blocks are shown in a particular order, in someexamples the steps may be performed in different orders. Additionally oralternatively, certain blocks may be omitted, combined, or sub-dividedinto separate blocks.

In block 302, the playback device receives audio data from an audiosource, such as a television or other video display device. In block304, the playback device determines whether the audio source indicatesthe incoming audio data to be in a compressed format. For example, theincoming audio data may include a channel status block (CSB) or otherindicator that designates whether the incoming audio data is in anuncompressed format (e.g., PCM) or a compressed format.

In incoming digital audio data, each sub-frame may contain a channelstatus bit. A digital audio block may contain 192 channel sub-frames,and accordingly there may be 192 status bits per channel that togetherform a channel status block (CSB). The CSB may carry status informationregarding the channel's digital audio information. This information caninclude whether the audio data is standard PCM or if it has beenmodified according to a compression scheme. In some instances, thesecond bit in a channel status bit array indicates whether the audio isencoded using linear PCM (logic 0) or if the audio has been compressed(logic 1). The CSB can also convey other information, such as samplerate, emphasis, bit depth, error correction data, etc. This example isprovided for purposes of illustration only. Alternatively, other tags orindicia either present in the audio data itself, such as metadata orother such indications, may provide a designation to the playback devicethat the audio data is compressed.

As noted previously, such indications are not necessarily reliable, anda mis-match between the format indicated by such a tag and the actualformat of the incoming audio could lead to poor outcomes and undesirableuser experiences (e.g., blasting undesirable and annoying noises as theplayback device processes the audio as PCM when the audio is actuallyencoded in a compressed format).

If, in block 304, the audio source indicates the audio to be compressed(e.g., based on an indication in the CSB), the process 300 continues toblock 306 in which the playback device evaluates N frames of the audiodata, and in block 308, the playback device determines the audio formatbased on that data examination. For example, the playback device canevaluate 2 or more frames of audio data, with each frame including 128samples. In these blocks, the playback device inspects the incomingaudio directly to assess the audio format (as opposed to relying on theCSB or other tag provided by the video display device).

In some examples, incoming digital audio that has been encoded using acompressed format (e.g., any non-linear-PCM encoding scheme) may comportto IEC Standard 61937:2020, published Jan. 6, 2020 by the InternationalElectrotechnical Commission, which is hereby incorporated by referencein its entirety. However, the principles described herein can be appliedto digital audio that comports to other standards or includes otherformats for conveying compression format data.

In some examples, the playback device can examine N frames (e.g., 2frames, each including 128 samples) to scan for sync words. As one ofskill in the art will appreciate, a sync word may be one predefined word(or one of several predefined words) with a specific bit pattern thatdesignates the beginning of each frame and allows system synchronizationto be obtained. For example, the sync word may be a 64-bit PaPb syncword. In some examples, the playback device can examine a sufficientnumber of frames of the audio data to identify at least two occurrencesof the sync word (e.g., in sequential, contiguous frames). This canreduce the risk of erroneously “detecting” a sync word in PCM data whereit is not intended.

In certain compressed audio standards, the bits subsequent to the syncword describe the compression format of the audio data, for exampleindicating the audio data as being encoded according to Dolby Digital,DTS, etc. For example, the 64 bits following the 64-bit PaPb sync word(e.g., PcPd) may indicate a particular compressed encoding format. Insome examples, there may be a finite and predefined number of validsequences of data following the sync word, each of which corresponds toa particular encoding format.

The process 300 continues in block 310 with determining whether theaudio is encoded in a compressed format. For example, if no valid audioformat is found in block 308 (e.g., data in the 64 bits following thesync word does not correspond to any predefined format indicating aparticular encoding format), then no audio is output (block 314). Thisreflects a scenario in which the video display device has indicated theincoming audio is compressed (e.g., via the CSB) while inspection of theaudio data via the playback device has disconfirmed this, finding novalid encoding format. As such, the video display device's indicationmay be erroneous, and so no audio is output. A response of no output maybe particularly appropriate in this case, as playing back compressedaudio utilizing a PCM scheme can result in a jarring, annoying, andundesirable audio output. As such, it is better for the user'sexperience to have no audio output in such a scenario, rather than riskbombarding the user with cacophonous audio.

Returning to block 310, if a valid audio format is found in block 308(e.g., data in the 64 bits following the sync words corresponds to apredefined format indicating a particular encoding format), then theplayback device has confirmed the audio is encoded in a compressedformat. The process 300 may then continue to block 312 to determinewhether the encoding format is supported. Although a particularcompressed encoding format can be identified via inspection of the audiodata, the playback device may not support decoding of all identifiableencoding formats. For example, the playback device may support playbackof audio encoded according to the DTS standard, while not supportingplayback of audio encoded according to the Dolby Atmos standard. If theencoding format is not supported, then the process 300 terminates inblock 314 with no output. Conversely, if the encoding format issupported, then the process continues in block 316 with sending the datastream to the appropriate decoder for processing and eventual playback.This reflects the scenario in which the format indicated by the videodisplay device (a compressed audio format as indicated in decision block304) matches with the format identified by inspection of the audio datavia the playback device (as indicated in decision block 310). As such,it is likely that the audio data is indeed encoded in the identifiedcompressed format, and playback can proceed accordingly.

As noted above, if (1) the audio format is unsupported (block 312) or(2) the audio is determined not to be encoded in a compressed format(block 310) while the source indicates compressed audio (block 304), noaudio may be output (block 314). In such scenarios, in addition toinhibiting audio playback, an alert, error message, or other suitableoutput can be provided. For example, an indication of the particularfailure can be output to a user via a control device (e.g., controldevice 130 a of FIG. 1H), or may be provided as audible output via aplayback device, visual output displayed via the display device, or asany other suitable notification. Additionally or alternatively, a reportof the particular error can be transmitted to remote computing devicesassociated with a device manufacturer, warranty provider, media contentprovider, or other entity. In some examples, the particular format ofaudio content provided to the source may be modified based at least inpart on error reports generated via the playback device.

Returning to block 304, if the source indicates the audio is notcompressed (e.g., the audio data is indicated to be in PCM format viathe CSB), then the process proceeds to blocks 318 and 320 to examine Nframes of audio data and determine the audio format based on dataexamination. These blocks can be similar to blocks 306 and 308 describedpreviously. For example, the audio data can be scanned for a sync wordand bits subsequent to the identified sync word can be evaluated forcorrespondence with predefined values that designate particular encodingformats.

In block 322, the playback device determines whether the audio isencoded in a compressed format, similar to block 310 described above.For example, if examination of the audio data in block 320 results inidentification of a particular compression format (e.g., a sync word isfound and data in the 64 bits following the sync word corresponds to apredefined format indicating a particular encoding format), the processcontinues to block 312 to determine whether the format is supported, andthen either to no output (block 314) if the output is not supported orto the appropriate decoder (block 316) if the particular encoding formatis supported. This flow reflects the scenario in which the sourceindicates the incoming audio to be uncompressed (e.g., PCM), yetexamination of the data via the playback device (blocks 318 and 320)contradicts this indication. In this scenario, the designation from thesource is overridden, the audio is played back (if the particular formatis supported by the playback device). In contrast to the scenario inwhich compressed audio data is played back as PCM (resulting in amachine-gun sound), attempted playback of PCM-encoded audio data usinganother decoding scheme (e.g., Dolby Digital) will generally fail andprovide no output. As such, there is less risk of attempting playback inthe case of a mismatch between the non-compression identified by thesource and the compressed format identified by inspection of the audiodata by the playback device.

Returning to block 322, if the audio is not encoded in a compressedformat (e.g., either no sync word is found or data subsequent to thesync word does not correspond to indication of a compression format),then the audio is output utilizing a PCM processing scheme. This flowreflects a scenario in which the designation via the audio source (block304) as uncompressed PCM audio (block 304) matches with thedetermination made by the playback device that the audio is uncompressed(block 322). As such, the PCM format has been confirmed, and playbackcan proceed accordingly in block 324.

The process 300 illustrates one sample flow for a particular block ofaudio data (e.g., containing N number of frames). However, the processcan be performed iteratively and/or continuously on incoming data. Forexample, the audio output from a video display device or other sourcemay be changed, and this change may include different encoding formats(e.g., a user may switch from one streaming service that encodes audiodata via PCM and another streaming service that encodes audio data viaDolby Digital). As such, continuous analysis of indications providedfrom an audio source (e.g., CSB) and examination of audio data (e.g.,identifying sync words and inspecting subsequent data) can be used toalter the processing scheme applied to the incoming audio data inreal-time or near real-time.

FIG. 4 is a flow diagram of another process 400 for decoding audio datain accordance with examples of the present technology. In some examples,the process 400 includes one or more instructions stored in memory(e.g., the memory 112 b of FIG. 1) and executed by one or moreprocessors (e.g., the processor 112 a of FIG. 1) of a playback device(e.g., the playback device 110 of FIG. 1, the playback device 205 ofFIG. 2). Although the blocks are shown in a particular order, in someexamples the steps may be performed in different orders. Additionally oralternatively, certain blocks may be omitted, combined, or sub-dividedinto separate blocks.

The process 400 illustrates an example flow for handling a potentialtransition of incoming audio data from a compressed audio format to anuncompressed audio format. For example, a video display device may beoutputting audio content in a compressed format while streaming a moviefrom a first media content provider. When a user switches to broadcasttelevision, the accompanying audio data output from the display devicemay be encoded in an uncompressed format (e.g., PCM). As notedpreviously, outputting compressed audio utilizing a PCM processingscheme can lead to highly undesirable user experiences, and accordinglyit can be advantageous to introduce a gating logic to confirm anyindication of a transition from compressed audio to uncompressed audiobefore processing the audio data utilizing a PCM processing scheme.

In block 402, the playback device receives encoded compressed audio(e.g., Dolby Digital, DTS Digital Surround, etc.) from an audio source(e.g., a television, video streaming device, etc.). In block 404, theplayback device can decode and play back the audio data, for exampleusing at least a portion of the process 300 described above with respectto FIG. 3.

In block 406, the playback device receives additional subsequent audiodata from the audio source. This subsequent data can be examined inblocks 408 and 410 to determine whether the audio is in a compressedformat and to optionally identify the particular encoding format. Theseblocks 408 and 410 can proceed similar to blocks 306 and 308 describedabove with respect to FIG. 3. For example, N frames of additional audiodata can be examined to identify a sync word (optionally confirming thesync word by identifying two or more sequential occurrences). The audiodata can be examined to determine an audio format (e.g., by examiningdata subsequent to the sync word for correspondence to one of apredefined number of valid formats that indicate a particular compressedencoding format).

In block 412, if the additional audio is determined to be encoded in acompressed format, then the audio is sent to an appropriate decoder 414.Alternatively, if the particular compressed format is not supported bythe playback device, audio playback can be ceased. In some examples, theappropriate decoder in block 414 may be different from the decoder beingpreviously applied to the incoming audio data. As such, based on thedetermination in block 410, the playback device may adjust playback byswitching to a different decoding scheme.

If, in block 414, the audio is determined not to be encoded in acompressed format (e.g., inspection of the data in block 410 indicatesthe audio data is PCM), then in block 416 playback can be delayed whilethe process is repeated on subsequent incoming audio data. For example,the process can return to block 408 for subsequent data while noplayback occurs. Only when multiple blocks of audio data (e.g., eachincluding N number of frames) have been evaluated and each beenidentified as PCM is the audio data confirmed as PCM, and then in block418 the playback device can play back the audio data according to a PCMprocessing scheme. In some examples, the delay in block 416 can bebetween about 10 ms and about 1 second, or between about 50 ms and about500 ms, or about 100 ms. This delay and confirmation (block 416) canadvantageously reduce the risk that non-PCM audio is output according toa PCM processing scheme. Without such a delay and confirmation, theplayback device may erroneously detect uncompressed audio input forexample, while a user is changing channels or otherwise adjusting theaudio source. The intermittent noise or jitter may not actually beencoded as PCM and yet may not be recognized as compressed audio data.Accordingly, to avoid outputting such noise or jitter as PCM, the delayand confirmation (block 416) refrains from switching from a non-PCMdecoding scheme to a PCM decoding scheme until sufficient time haspassed and the subsequent audio has been confirmed as being in PCMformat.

FIG. 5 is a diagram of a state machine 500 for decoding audio data inaccordance with examples of the present technology. The processing flowsillustrated in FIG. 5 can correspond at least in part of the processes300 and 400 described previously. In some examples, the state machine500 reflects one or more instructions stored in memory (e.g., the memory112 b of FIG. 1) that can be executed by one or more processors (e.g.,the processor 112 a of FIG. 1) of a playback device (e.g., the playbackdevice 110 of FIG. 1, the playback device 205 of FIG. 2).

As shown in FIG. 5, an input (e.g., an audio input from a video displaydevice or other source) proceeds to block 502. If non-zero frames arenot found, this indicates there is no incoming audio data and decisionblock 502 iteratively repeats until non-zero frames are found. Oncenon-zero frames are found in block 502, in block 504 N input frames aresearched for valid sync word(s) and an encoding tag. For example, asdescribed above with respect to FIG. 3, a sync word can be identifiedand subsequent data can be examined for an encoding tag (e.g., data thatindicates a particular type of compressed encoding format). Next, inblock 506, if no valid sync word and/or no encoding tag are found withinN frames, then PCM is extracted in block 508. The extracted PCM can thenbe processed according to a PCM processing scheme for audio playback. Inblock 510, subsequent audio continues to be evaluated to determine if avalid sync word and encoding tag is found within N frames. If so, theprocess returns to block 502. If not, then the subsequent audiocontinues to be extracted as PCM for audio playback.

Returning to block 506, if a valid sync word and encoding tag are found,then in decision block 512 the playback device determines whether thenull databurst is terminated. If the null databurst is terminated inblock 512, the process returns to input to block 502. If the nulldataburst is not encountered, the process continues to block 514 toidentify two contiguous identical tags. For example, a sync word andsubsequent tag may be identified in block 504. Subsequent frames can beevaluated and, if another occurrence of the same sync word and the sameencoding tag are not identified within N frames, then the audio data isextracted as PCM in block 508. This reflects a scenario in which theinitial identification of a sync word and encoding tag was likely afalse positive, since a subsequent repetition of the sync word andencoding tag was not found.

Alternatively, if a contiguous and identical sync word and encoding tagare found in block 514, the process continues to block 516 to determinewhether the encoding format is supported. If the format is notsupported, the process returns to block 512 to determine whether thenull databurst is terminated. In this manner, if the encoding format isnot supported, there is no audio playback. This loop continues untilsubsequent audio data is either extracted as PCM or is encoded in acompressed format supported by the playback device.

In block 518, if the encoding format is supported (block 516), thedatastream is aligned. For example, using the sync word (block 504), thedatastream can be aligned for synchronous playback (e.g., for the audioto be played back in synch with video play back via the video displaydevice). If, in block 520, an alignment failure is detected, the processreturns to block 502. If instead, there is no alignment failure, thenthe process continues to block 522, in which, while there are no signaldiscontinuities, the databurst is extracted. A discontinuity can beidentified when an identified sync word is not in the correct positionrelative to the previous occurrence (e.g., every 1536 frames for DOLBYDIGITAL). The extracted databurst can be decoded using an appropriatedecoding scheme and the audio played back via the playback device.

If, in block 524, a discontinuity is not detected, the extractioncontinues in block 522. If, in contrast, a discontinuity is detected inblock 524, the process returns to input to block 502. As such, audiodetermined to be encoded using a particular compression format (asidentified in block 504 and confirmed in block 514) can be aligned andplayed back so long as there are no discontinuities, which may indicatea change in the audio input format (e.g., changing from one streamingservice to another).

IV. Conclusion

The above discussions relating to playback devices, controller devices,playback zone configurations, and media content sources provide onlysome examples of operating environments within which functions andmethods described below may be implemented. Other operating environmentsand/or configurations of media playback systems, playback devices, andnetwork devices not explicitly described herein may also be applicableand suitable for implementation of the functions and methods.

The description above discloses, among other things, various examplesystems, methods, apparatus, and articles of manufacture including,among other components, firmware and/or software executed on hardware.It is understood that such examples are merely illustrative and shouldnot be considered as limiting. For example, it is contemplated that anyor all of the firmware, hardware, and/or software examples or componentscan be embodied exclusively in hardware, exclusively in software,exclusively in firmware, or in any combination of hardware, software,and/or firmware. Accordingly, the examples provided are not the onlyways) to implement such systems, methods, apparatus, and/or articles ofmanufacture.

Additionally, references herein to “example” means that a particularfeature, structure, or characteristic described in connection with theexample can be included in at least one example or embodiment of aninvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same example, norare separate or alternative examples mutually exclusive of otherexamples. As such, the examples described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother examples.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain examples of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring examples of the examples. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforegoing description of examples.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible,non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on,storing the software and/or firmware.

The disclosed technology is illustrated according to various examplesdescribed below. Various examples of the disclosed technology aredescribed as numbered clauses (1, 2, 3, etc.) for convenience. These areprovided as examples and do not limit the disclosed technology. It isnoted that any of the dependent Clauses may be combined in anycombination, and placed into a respective independent Clause. The otherClauses can be presented in a similar manner.

Clause 1. A method of playing back audio content comprising: receiving,at a playback device, audio data from a video display device; receivingan indication from the video display device that the audio data isencoded in a compressed audio format; determining, independently ofreceiving the indication from the video display device that the audiodata is encoded in the compressed audio format, whether the audio datais encoded in a compressed audio format; if the audio data is determinedto be encoded in the compressed audio format: selecting a decoder fromamong a plurality of decoders; decoding the audio data using theselected decoder; and playing back the decoded audio data via theplayback device; and if the audio data is determined not to be encodedin the compressed audio format: inhibiting playback of the audio data.

Clause 2. The method of Clause 1, wherein receiving the indication fromthe video display device that the audio data is encoded in a compressedaudio format comprises detecting a channel status block (CSB) indicatingthat the audio data is encoded in a compressed audio format.

Clause 3. The method of any one of the preceding Clauses, whereindetermining, independently of receiving the indication from the videodisplay device that the audio data is encoded in the compressed audioformat, whether the audio data is encoded in a compressed audio formatcomprises: searching a predetermined number of frames of the audio datato detect a sync word; and analyzing a data burst of the audio datasubsequent to the sync word to identify an encoding scheme.

Clause 4. The method of any one of the preceding Clauses, furthercomprising: after detecting the sync word; searching a secondpredetermined number of frames subsequent to the sync word to identify asecond repetition of the sync word.

Clause 5. The method of any one of the preceding Clauses, whereinanalyzing the data burst of the audio data subsequent to the sync wordcomprises determining whether the data burst corresponds to one of aplurality of predetermined valid sequences corresponding to an encodingscheme, wherein: if the data burst corresponds to one of the pluralityof predetermined valid sequences, determining that the audio data isencoded in a compressed audio format; and if the data burst does notcorrespond to one of the plurality of predetermined valid sequences,determining that the audio data is not encoded in a compressed audioformat.

Clause 6. The method of any one of the preceding Clauses, furthercomprising: playing back decoded audio data via the playback device; andwhile playing back the decoded audio data: receiving, at the playbackdevice, additional audio data from the audio source; evaluating theadditional audio data to determine whether the additional audio data isencoded in a compressed audio format; if the audio data is determinednot to be encoded in a compressed audio format, initiating playback ofthe additional audio data only after a predetermined delay.

Clause 7. The method of any one of the preceding Clauses, wherein thevideo display device comprises a television, and wherein the playbackdevices comprises a soundbar.

Clause 8. The method of any one of the preceding Clauses, wherein theplurality of decoders comprises at least two or more of: a DOLBY DIGITALdecoder; a DOLBY DIGITAL PLUS decoder, a MAP decoder; a DOLBY ATMOSdecoder; a DTS:X decoder; or a MAP decoder.

Clause 9. A playback device configured comprising: at least oneamplifier configured to drive an audio transducer; one or moreprocessors; and a computer-readable memory storing instructions that,when executed by the one or more processors, cause the playback deviceto perform operations comprising: receiving, at a playback device, audiodata from a video display device; receiving an indication from the videodisplay device that the audio data is encoded in a compressed audioformat; determining, independently of receiving the indication from thevideo display device that the audio data is encoded in the compressedaudio format, whether the audio data is encoded in a compressed audioformat; if the audio data is determined to be encoded in the compressedaudio format: selecting a decoder from among a plurality of decoders;decoding the audio data using the selected decoder; and playing back thedecoded audio data via the playback device; and if the audio data isdetermined not to be encoded in the compressed audio format: inhibitingplayback of the audio data.

Clause 10. The playback device of any one of the preceding Clauses,wherein receiving the indication from the video display device that theaudio data is encoded in a compressed audio format comprises detecting achannel status block (CSB) indicating that the audio data is encoded ina compressed audio format.

Clause 11. The playback device of any one of the preceding Clauses,wherein determining, independently of receiving the indication from thevideo display device that the audio data is encoded in the compressedaudio format, whether the audio data is encoded in a compressed audioformat comprises: searching a predetermined number of frames of theaudio data to detect a sync word; and analyzing a data burst of theaudio data subsequent to the sync word to identify an encoding scheme.

Clause 12. The playback device of any one of the preceding Clauses,wherein the operations further comprise: after detecting the sync word,searching a second predetermined number of frames subsequent to the syncword to identify a second repetition of the sync word.

Clause 13. The playback device of any one of the preceding Examples,wherein analyzing the data burst of the audio data subsequent to thesync word comprises determining whether the data burst corresponds toone of a plurality of predetermined valid sequences corresponding to anencoding scheme, wherein: if the data burst corresponds to one of theplurality of predetermined valid sequences, determining that the audiodata is encoded in a compressed audio format; and if the data burst doesnot correspond to one of the plurality of predetermined valid sequences,determining that the audio data is not encoded in a compressed audioformat.

Clause 14. The playback device of any one of the preceding Clauses,wherein the operations further comprise: playing back decoded audio datavia the playback device; and while playing back the decoded audio data:receiving, at the playback device, additional audio data from the audiosource; evaluating the additional audio data to determine whether theadditional audio data is encoded in a compressed audio format; if theaudio data is determined not to be encoded in a compressed audio format,initiating playback of the additional audio data only after apredetermined delay.

Clause 15. Tangible, non-transitory computer-readable medium storinginstructions that, when executed by the one or more processors of aplayback device, cause the playback device to perform operationscomprising: receiving, at a playback device, audio data from a videodisplay device; receiving an indication from the video display devicethat the audio data is encoded in a compressed audio format;determining, independently of receiving the indication from the videodisplay device that the audio data is encoded in the compressed audioformat, whether the audio data is encoded in a compressed audio format;if the audio data is determined to be encoded in the compressed audioformat: selecting a decoder from among a plurality of decoders; decodingthe audio data using the selected decoder; and playing back the decodedaudio data via the playback device; and if the audio data is determinednot to be encoded in the compressed audio format: inhibiting playback ofthe audio data.

Clause 16. The computer-readable medium of any one of the precedingClauses, wherein receiving the indication from the video display devicethat the audio data is encoded in a compressed audio format comprisesdetecting a channel status block (CSB) indicating that the audio data isencoded in a compressed audio format.

Clause 17. The computer-readable medium of any one of the precedingClauses, wherein determining, independently of receiving the indicationfrom the video display device that the audio data is encoded in thecompressed audio format, whether the audio data is encoded in acompressed audio format comprises: searching a predetermined number offrames of the audio data to detect a sync word; and analyzing a databurst of the audio data subsequent to the sync word to identify anencoding scheme.

Clause 18. The computer-readable medium of any one of the precedingClauses, wherein the operations further comprise: after detecting thesync word, searching a second predetermined number of frames subsequentto the sync word to identify a second repetition of the sync word.

Clause 19. The computer-readable medium of any one of the precedingClauses, wherein analyzing the data burst of the audio data subsequentto the sync word comprises determining whether the data burstcorresponds to one of a plurality of predetermined valid sequencescorresponding to an encoding scheme, wherein: if the data burstcorresponds to one of the plurality of predetermined valid sequences,determining that the audio data is encoded in a compressed audio format;and if the data burst does not correspond to one of the plurality ofpredetermined valid sequences, determining that the audio data is notencoded in a compressed audio format.

Clause 20. The computer-readable medium of any one of the precedingClauses, wherein the operations further comprise: playing back decodedaudio data via the playback device; and while playing back the decodedaudio data: receiving, at the playback device, additional audio datafrom the audio source; evaluating the additional audio data to determinewhether the additional audio data is encoded in a compressed audioformat; if the audio data is determined not to be encoded in acompressed audio format, initiating playback of the additional audiodata only after a predetermined delay.

1. A playback device comprising: at least one amplifier configured todrive an audio transducer; one or more processors; and data storagestoring instructions that, when executed by the one or more processors,cause the playback device to perform operations comprising: receiving,at the playback device, first audio data from a video display device;receiving an indication from the video display device that the firstaudio data is encoded in a compressed audio format; selecting a decoderfrom among a plurality of decoders; decoding the first audio data usingthe selected decoder; playing back the decoded first audio data via theplayback device; while playing back the first audio data, receiving, atthe playback device, second audio data from the video display device,the second audio data encoded via an uncompressed pulse-code modulation(PCM) format; determining, via the playback device, that the secondaudio data is encoded in the uncompressed PCM format; after determiningthat the second audio data is encoded in the uncompressed PCM format,initiating playback of the second audio data only after a predetermineddelay.
 2. The playback device of claim 1, wherein receiving theindication from the video display device that the first audio data isencoded in the compressed audio format comprises detecting a channelstatus block (CSB) indicating that the first audio data is encoded in acompressed audio format.
 3. The playback device of claim 1, wherein theoperations further comprise determining, independently of receiving theindication from the video display device that the first audio data isencoded in the compressed audio format, that the first audio data isencoded in the compressed audio format.
 4. The playback device of claim3, wherein determining, independently of receiving the indication fromthe video display device that the first audio data is encoded in thecompressed audio format, that the first audio data is encoded in thecompressed audio format comprises: searching a predetermined number offrames of the first audio data to detect a sync word; and analyzing adata burst of the first audio data subsequent to the sync word toidentify an encoding scheme.
 5. The playback device of claim 4, whereinthe operations further comprise: after detecting the sync word;searching a second predetermined number of frames subsequent to the syncword to identify a second repetition of the sync word.
 6. The playbackdevice of claim 4, wherein analyzing the data burst of the first audiodata subsequent to the sync word comprises determining that the databurst corresponds to one of a plurality of predetermined valid sequencescorresponding to an encoding scheme.
 7. The playback device of claim 1,wherein the plurality of decoders comprises at least two or more of: aDOLBY DIGITAL decoder; a DOLBY DIGITAL PLUS decoder, a MAP decoder; aDOLBY ATMOS decoder; a DTS:X decoder; or a MAP decoder.
 8. A method ofplaying back audio content comprising: receiving, at a playback device,first audio data from a video display device; receiving an indicationfrom the video display device that the first audio data is encoded in acompressed audio format; selecting a decoder from among a plurality ofdecoders; decoding the first audio data using the selected decoder;playing back the decoded first audio data via the playback device; whileplaying back the first audio data, receiving, at the playback device,second audio data from the video display device, the second audio dataencoded via an uncompressed pulse-code modulation (PCM) format;determining, via the playback device, that the second audio data isencoded in the uncompressed PCM format; after determining that thesecond audio data is encoded in the uncompressed PCM format, initiatingplayback of the second audio data only after a predetermined delay. 9.The method of claim 8, wherein receiving the indication from the videodisplay device that the first audio data is encoded in the compressedaudio format comprises detecting a channel status block (CSB) indicatingthat the first audio data is encoded in a compressed audio format. 10.The method of claim 8, further comprising determining, independently ofreceiving the indication from the video display device that the firstaudio data is encoded in the compressed audio format, that the firstaudio data is encoded in the compressed audio format.
 11. The method ofclaim 10, wherein determining, independently of receiving the indicationfrom the video display device that the first audio data is encoded inthe compressed audio format, that the first audio data is encoded in thecompressed audio format comprises: searching a predetermined number offrames of the first audio data to detect a sync word; and analyzing adata burst of the first audio data subsequent to the sync word toidentify an encoding scheme.
 12. The method of claim 11, furthercomprising: after detecting the sync word; searching a secondpredetermined number of frames subsequent to the sync word to identify asecond repetition of the sync word.
 13. The method of claim 11, whereinanalyzing the data burst of the first audio data subsequent to the syncword comprises determining that the data burst corresponds to one of aplurality of predetermined valid sequences corresponding to an encodingscheme.
 14. The method of claim 8, wherein the plurality of decoderscomprises at least two or more of: a DOLBY DIGITAL decoder; a DOLBYDIGITAL PLUS decoder, a MAP decoder; a DOLBY ATMOS decoder; a DTS:Xdecoder; or a MAP decoder.
 15. One or more tangible, non-transitorycomputer-readable media storing instructions that, when executed by theone or more processors of a playback device, cause the playback deviceto perform operations comprising: receiving, at the playback device,first audio data from a video display device; receiving an indicationfrom the video display device that the first audio data is encoded in acompressed audio format; selecting a decoder from among a plurality ofdecoders; decoding the first audio data using the selected decoder;playing back the decoded first audio data via the playback device; whileplaying back the first audio data, receiving, at the playback device,second audio data from the video display device, the second audio dataencoded via an uncompressed pulse-code modulation (PCM) format;determining, via the playback device, that the second audio data isencoded in the uncompressed PCM format; after determining that thesecond audio data is encoded in the uncompressed PCM format, initiatingplayback of the second audio data only after a predetermined delay. 16.The one or more computer-readable media of claim 15, wherein receivingthe indication from the video display device that the first audio datais encoded in the compressed audio format comprises detecting a channelstatus block (CSB) indicating that the first audio data is encoded in acompressed audio format.
 17. The one or more computer-readable media ofclaim 15, wherein the operations further comprise determining,independently of receiving the indication from the video display devicethat the first audio data is encoded in the compressed audio format,that the first audio data is encoded in the compressed audio format. 18.The one or more computer-readable media of claim 17, whereindetermining, independently of receiving the indication from the videodisplay device that the first audio data is encoded in the compressedaudio format, that the first audio data is encoded in the compressedaudio format comprises: searching a predetermined number of frames ofthe first audio data to detect a sync word; and analyzing a data burstof the first audio data subsequent to the sync word to identify anencoding scheme.
 19. The one or more computer-readable media of claim18, wherein the operations further comprise: after detecting the syncword; searching a second predetermined number of frames subsequent tothe sync word to identify a second repetition of the sync word.
 20. Theone or more computer-readable media of claim 18, wherein analyzing thedata burst of the first audio data subsequent to the sync word comprisesdetermining that the data burst corresponds to one of a plurality ofpredetermined valid sequences corresponding to an encoding scheme.